Oxygen transport membrane reactors for decarbonization

Abstract

A method and system for decarbonization of a hydrocarbon conversion process such as steam methane reforming process for hydrogen production utilizing oxygen transport membrane reactors. The system employs catalyst-containing reforming reactors for converting natural gas into synthesis gas which is further treated in high temperature or medium temperature water gas shift reactors and fed to a hydrogen PSA to produce hydrogen product. The system further employs oxygen transport membrane reactors thermally coupled to reforming reactors and configured to oxy-combust about 90% to about 95% of combustibles in PSA tail gas that may be optionally mixed with natural gas. The oxy-combustion product stream leaving the oxygen transport membrane reactors contains about 90% of the carbon provided to the feed of the reforming reactor. The carbon dioxide in the oxy-combustion product stream can be recovered and further purified for utilization or geologic storage or liquefied to form a liquid carbon dioxide product.

What is claimed is: 
     
         1 . A method for decarbonization of a hydrocarbon conversion process for hydrogen production utilizing an oxygen transport membrane-based reforming system, wherein said system composes at least one reforming reactor and at least one oxygen transport membrane reactor disposed in a reactor housing proximate to said at least one reforming reactor, the method comprising the steps of:
 separating oxygen from an oxygen containing stream with one or more catalyst-containing oxygen transport membrane reactors to produce an oxygen permeate and an oxygen-depleted retentate stream, the catalyst being contained within tubes on the permeate side of the oxygen transport membrane reactors;   feeding a fuel stream to a permeate side of the oxygen transport membrane elements and reacting same with the oxygen permeate to generate a reaction products stream, oxy-combustion products stream and heat;   transferring the heat via convection to the oxygen-depleted retentate stream and via radiation to at least one catalyst-containing reforming reactor configured to produce a synthesis gas stream;   reforming a combined feed stream comprising natural gas and steam in said at least one reforming reactor in the presence of a reforming catalyst and radiant heat transferred from the oxygen transport membrane reactor to produce a reformed synthesis gas stream comprising hydrogen and carbon monoxide;   treating the synthesis gas product stream in a separate high, and/or medium and/or low temperature shift reactor to form a hydrogen-enriched synthesis gas stream; and   treating the hydrogen-enriched synthesis gas stream in a hydrogen PSA; and   recovering a hydrogen product stream and a tail gas stream;   wherein a portion of the fuel gas stream required for the oxygen transport membrane reactor is the tail gas stream from the hydrogen PSA, optionally mixed with supplementary hydrocarbon fuel, and wherein no portion of the reformed synthesis gas stream leaving the reforming reactor is directly recycled back to the oxygen transport membrane reactor;   wherein the oxygen transport membrane reactors combust about 90% to about 95% of the combustibles in the fuel gas, and oxy-combustion product stream leaving the oxygen transport membrane reactors contains about 90% of the carbon contained in the natural gas provided to the reforming reactor.   
     
     
         2 . The method of  claim 1  wherein the heat generated as a result of the reaction of the fuel stream with permeated oxygen is transferred: (i) to the reforming reactor; (ii) to the unreformed fuel gas stream present in the reactively-driven, catalyst-containing oxygen transport membrane reactor; and (iii) to an oxygen-depleted retentate stream. 
     
     
         3 . A hydrogen production system comprising:
 an oxygen transport membrane-based reactor housing comprising:
 a reforming reactor disposed in the reactor housing and configured to reform a hydrocarbon containing feed stream in the presence of a reforming catalyst disposed in the reforming reactor and heat to produce a reformed synthesis gas stream; 
 a reactively-driven, catalyst-containing oxygen transport membrane reactor disposed in the reactor housing proximate the reforming reactor and configured to receive a hydrocarbon containing fuel stream and react said stream with permeated oxygen and generate a first stream of reaction products and heat; 
 a water gas shift reactor unit; and 
 a hydrogen PSA unit, 
   wherein the oxygen transport membrane reactors combust about 90% to about 95% of the combustibles in the fuel gas, and the oxy-combustion products stream leaving the oxygen transport membrane reactors contains about 90% of the carbon provided to the feed of the reforming reactor.   
     
     
         4 . The system of  claim 3  wherein the reactively-driven, catalyst-containing oxygen transport membrane reactor further comprises a plurality of oxidation catalyst-containing oxygen transport membrane tubes defining an oxidant side and a reactant side and configured to separate oxygen from an oxygen containing stream contacting the oxidant side and permeate separated oxygen to the reactant side through oxygen ion transport when subjected to the elevated operational temperature and a difference in oxygen partial pressure across the at least one oxygen transport membrane tube. 
     
     
         5 . A method for decarbonizing a hydrogen production process that utilizes a steam methane reformer; wherein the feed to said reformer comprises natural gas, wherein said natural gas is converted into a syngas, and wherein a portion of the tail gas fuel stream derived from said syngas is combusted in one or more oxygen transport membrane reactors producing reaction heat, wherein a portion of the heat required to sustain the endothermic reforming reaction in said reformer is provided by said reaction heat via radiant heat transfer, followed by processing the combustion product stream exiting the oxygen transport membrane reactor to produce a concentrated CO2 stream containing from about 90% CO2 by volume to about 95% CO2 by volume. 
     
     
         6 . The method of  claim 5  wherein a CO2 product of at least 99.5% CO2 by volume is produced from the concentrated CO2 stream by a cryogenic liquefaction process. 
     
     
         7 . The method of  claim 6  whereby the non-condensable gases rejected from the cryogenic process are recycled back to the feed of the reformer system. 
     
     
         8 . The method of  claim 5  wherein the concentrated CO2 stream is further processed in a PSA process or a TSA process to produce a higher purity CO2 stream for compression and carbon sequestration or use as a feedstock to a downstream process. 
     
     
         9 . The method of  claim 5  where the concentrated CO2 stream is subsequently utilized as part of the feed of a dry-reforming process. 
     
     
         10 . The method of  claim 8  where the concentrated CO2 stream is subsequently utilized as part of the feed of a dry-reforming process, a methanol synthesis process, or a Fisher-Tropsch synthesis process or a cement-curing process or a cement production process. 
     
     
         11 . The method of  claim 5  wherein said concentrated CO2 stream is subjected to catalytic oxidation with a supplemental oxygen containing stream to produce a super-critical CO2 product comprising at least 99% CO2 by volume. 
     
     
         12 . The method of  claim 5  wherein said concentrated CO2 stream is subjected to methanation process to produce a moderate purity super-critical CO2 product containing CO2 in a concentration of about at least 95% CO2 by volume, CO in a concentration of less than about 1000 ppm by volume, and total hydrocarbons in a concentration less than about 5% by volume. 
     
     
         13 . The method of  claim 5 , wherein the tail gas is compressed, mixed with superheated steam and subjected to a water-gas shift reaction to provide a fuel stream containing less than about 8% by volume CO for the oxygen transport membrane reactor. 
     
     
         14 . The method of  claim 5 , wherein the tail gas is compressed, mixed with superheated steam and subjected to a methanation reaction to provide a fuel stream containing less than about 8% by volume CO for the oxygen transport membrane reactor. 
     
     
         15 . The method of  claim 5 , wherein tail gas is compressed, mixed with superheated steam and subjected to a water-gas shift reaction or methanation reaction to provide a fuel stream for the oxygen transport membrane reactor wherein the fuel stream chemical equilibrium carbon activity calculated at a temperature of about 500° C. and a pressure of about 9 hart has a value less than about 10. 
     
     
         16 . The method of  claim 5 , wherein the tail gas is compressed, mixed with superheated steam and subjected to a water-gas shift reaction or methanation reaction to provide a fuel stream for the oxygen transport membrane reactor wherein the fuel stream chemical equilibrium carbon activity calculated at a temperature of about 600° C. and a pressure of about 9 barg has a value less than about 5, preferably less than about 2.